Implications of increased intertidal inundation on seagrass net primary production
Implications of increased intertidal inundation on seagrass net primary production
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DOI：
10.1016/j.ecss.2024.108636
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发表时间：
2024-01-17
影响因子：
2.8
通讯作者：
Berg，Peter
中科院分区：
文献类型：
--
作者：
Lohrer，Andrew M.;Macdonald，Iain T.;Berg，Peter
海草草甸是生产力和功能重要的海底生境，在人类活动的压力下，世界许多地方的海草草甸正在减少。海底光的可用性与水深成反比，因此，与全球变暖有关的海平面上升可能会影响海草的生产力及其对沿海生态系统的贡献。通过潮汐振荡和距离海岸的海草床深度的自然变化，我们在新西兰使用水生涡动协方差每15分钟对海底氧交换进行量化，以更好地了解海平面上升对浅海草的影响。当海底光合有效辐射>87.5 μmol photons m−2s−1时，4个平均深度不同的地点（涨潮时为1.5-4.0 m深）是氧气的净生产者，在日照高峰时间，所有地点的净氧气生产量均>4 mmol m− 2 h − 1。当比较早晨（低潮）和晚上（高潮）的通量时，光衰减对溶解氧产生的影响是明显的，在一天中的这些时间到达水面的入射光水平相对相似。最浅的地点预计将获得最多的光线在海底和最多产。然而，第二个最浅的地点是最具生产力的，因为海草覆盖率较高，水更清澈（水柱中的光衰减较小）。海草覆盖率较高可能会减少沉积物再悬浮，同时增加光合能力（即，更多的光合生物量）。上海岸附近存在浑浊的水边缘和与气候相关的悬浮泥沙浓度变化可能会干扰海草草甸向岸迁移的预测，海草草甸已经因与上潮间带植被的相互作用而变得复杂（例如，红树林）和人类建造的结构（例如，海堤）。
Seagrass meadows are productive and functionally important seafloor habitats that are declining in many parts of the world under pressure from human activities. Seabed light availability is inversely related to water depth, thus sea level rise associated with global warming may impinge upon seagrass productivity and its contributions to coastal ecosystems. Across natural variation in seagrass bed depth driven by tidal oscillations and distance from shore, we quantified seafloor oxygen exchange every 15 min for three days and nights at sites in New Zealand using aquatic eddy covariance to better understand the implications of sea level rise on shallow seagrass. Four sites of differing mean depth (1.5–4.0 m deep at high tide) were net producers of oxygen when photosynthetically active radiation at the seabed was >87.5 μmol photons m−2s−1, with net oxygen production >4 mmol m−2h−1at all sites during peak sunlight hours. The effect of light attenuation on dissolved oxygen production was evident when comparing fluxes in the morning (low tide) and evening (high tide), with relatively similar incident light levels arriving at water surface at these times of day. The shallowest site was expected to receive the greatest amount of light at the seabed and be most productive. However, the second shallowest site was the most productive, due to higher seagrass cover and clearer water (less light attenuation in the water column). Higher cover of seagrass likely reduced sediment resuspension while increasing photosynthetic capacity (i.e., more photosynthetic biomass). The existence of turbid fringes of water near the upper shore and climate-related shifts in suspended sediment concentrations may interfere with predictions of shoreward migration of seagrass meadows, which are already complicated by interactions with upper intertidal vegetation (e.g., mangroves) and human built structures (e.g., seawalls).